?Grading Timber Desiring to grade timber mechanically, engineers studied the modulus of rupture in lb>in.2, for a sample of untreated green, 7 inch by

Chapter 13, Problem 4

(choose chapter or problem)

Grading Timber Desiring to grade timber mechanically, engineers studied the modulus of rupture in \(\mathrm{lb} / \text {in.}^{2}\), for a sample of untreated green, 7 inch by 9 inch, mixed oak timbers, sorted by grade: select structural, No. 1, No. 2, and below grade. A one-way ANOVA was performed to test \(H_{0:}: \mu_{\text {select }}=\mu_{\mathrm{No} .1}=\mu_{\mathrm{No} .2}=\mu_{\text {below grade }}\). The null hypothesis was rejected with a P-value of 0.018. The engineers proceeded to conduct Tukey’s test to determine which pairwise means differed using Minitab. The results are presented next. Which pairwise means differ? What do you conclude from the test?

Note: 1 = select structural, 2 = No. 1, 3 = No. 2, and  4 = below grade.

Text Transcription:

ln/in^2

H_0 : mu_select = mu_No.1 = mu_No.2 = mu_below grade